Pub Date : 2025-02-01DOI: 10.1016/j.ijrmms.2024.106008
Dowon Park
Previous observations of the roof stability analyses for deep-depth tunnels in continuum rock mass suggest that the critical roof failure mechanism involves a π/2-rotation of the failure envelope utilized in the analysis. In this study, the results obtained from the kinematic approach of the limit analysis and limit equilibrium method demonstrated that the failure profile of a roof collapse in a physical space is equivalent to the rotated and scaled shear strength envelope in the stress plane. An analytical technique employing parametric expressions is presented to account directly and accurately for the generalized Hoek–Brown criterion without requiring knowledge of its closed-form shear strength envelope or replacing it with approximated functions. The solutions obtained from the two independent methods, that is, the pure and lesser forms of the upper-bound approach, were identical owing to the rigid-block translational mechanism. In addition, several interesting aspects of the mechanics of incipient roof collapse are investigated by inspecting the stress state and failure mechanism in compliance with static force equilibrium and kinematic compatibility. The proposed method overcomes the limitations of conventional studies conducted in this category.
{"title":"Roof stability for rock cavities and tunnels: Revisiting limit state plastic analysis","authors":"Dowon Park","doi":"10.1016/j.ijrmms.2024.106008","DOIUrl":"10.1016/j.ijrmms.2024.106008","url":null,"abstract":"<div><div>Previous observations of the roof stability analyses for deep-depth tunnels in continuum rock mass suggest that the critical roof failure mechanism involves a <em>π</em>/2-rotation of the failure envelope utilized in the analysis. In this study, the results obtained from the kinematic approach of the limit analysis and limit equilibrium method demonstrated that the failure profile of a roof collapse in a physical space is equivalent to the rotated and scaled shear strength envelope in the stress plane. An analytical technique employing parametric expressions is presented to account directly and accurately for the generalized Hoek–Brown criterion without requiring knowledge of its closed-form shear strength envelope or replacing it with approximated functions. The solutions obtained from the two independent methods, that is, the pure and lesser forms of the upper-bound approach, were identical owing to the rigid-block translational mechanism. In addition, several interesting aspects of the mechanics of incipient roof collapse are investigated by inspecting the stress state and failure mechanism in compliance with static force equilibrium and kinematic compatibility. The proposed method overcomes the limitations of conventional studies conducted in this category.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"186 ","pages":"Article 106008"},"PeriodicalIF":7.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142974942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.ijrmms.2024.106022
Yuhao Liu , Keita Yoshioka , Tao You , Hanzhang Li , Fengshou Zhang
Significant volumes of water are injected into the subsurface for purposes such as maintaining reservoir pressure, enhancing production efficiency, or water disposal. In these operations, injection pressures are typically kept low to prevent the formation from fracturing. However, fractures may still be induced even at low injection pressures if the injected water cools the formation, causing thermal contraction. In this study, we numerically investigate thermally induced fractures during water injection using a variational thermo-hydro-mechanical phase-field model. Our simulation results show that cold water injection can nucleate multiple thermal fractures nearly orthogonal to a stimulated fracture, even if the injection pressure is below the fracturing pressure. Further simulation scenarios reveal that thermal fracture propagation is more likely with larger temperature differences, smaller in-situ stress anisotropy, and lower formation permeability. This study highlights the significant impact of thermal effects on fracture initiation and propagation, suggesting the need for careful consideration when regulating or managing fracture initiation during water injection.
{"title":"Thermally induced fracture modeling during a long-term water injection","authors":"Yuhao Liu , Keita Yoshioka , Tao You , Hanzhang Li , Fengshou Zhang","doi":"10.1016/j.ijrmms.2024.106022","DOIUrl":"10.1016/j.ijrmms.2024.106022","url":null,"abstract":"<div><div>Significant volumes of water are injected into the subsurface for purposes such as maintaining reservoir pressure, enhancing production efficiency, or water disposal. In these operations, injection pressures are typically kept low to prevent the formation from fracturing. However, fractures may still be induced even at low injection pressures if the injected water cools the formation, causing thermal contraction. In this study, we numerically investigate thermally induced fractures during water injection using a variational thermo-hydro-mechanical phase-field model. Our simulation results show that cold water injection can nucleate multiple thermal fractures nearly orthogonal to a stimulated fracture, even if the injection pressure is below the fracturing pressure. Further simulation scenarios reveal that thermal fracture propagation is more likely with larger temperature differences, smaller in-situ stress anisotropy, and lower formation permeability. This study highlights the significant impact of thermal effects on fracture initiation and propagation, suggesting the need for careful consideration when regulating or managing fracture initiation during water injection.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"186 ","pages":"Article 106022"},"PeriodicalIF":7.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143049846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.ijrmms.2024.106004
Gao-Feng Zhao, Yu-Hang Wu, Xin-Dong Wei
This paper introduces a method for constructing high-fidelity digital rock using digital grinding and deep learning, specifically for the Four-Dimensional Lattice Spring Model (4D-LSM). Initially, rock sequence images are captured with a self-designed digital grinding equipment. Bicubic interpolation is then applied to fill missing pixels, ensuring uniform resolution. The images are subsequently deblurred using DeblurGAN, a deep learning network trained with existing high-definition images. This process results in high-fidelity 3D true-color digital rock geometry reconstruction. An Artificial Neural Network (ANN) identifies mineral components, which are then mapped into the 4D-LSM to create the high-fidelity 3D true-color Grain-Based Model (GBM). The mechanical behavior of the GBM is analyzed using the 4D-LSM, incorporating strength reduction factors which can be easily calibrated through a modified Newton algorithm. Results demonstrate that the high-fidelity 3D true-color GBM accurately replicates the mechanical behavior and failure processes of granite, offering improved consistency with experimental data compared to homogeneous models.
{"title":"A high-fidelity digital rock representation based on digital grinding combined with deep learning for four-dimensional lattice spring model","authors":"Gao-Feng Zhao, Yu-Hang Wu, Xin-Dong Wei","doi":"10.1016/j.ijrmms.2024.106004","DOIUrl":"10.1016/j.ijrmms.2024.106004","url":null,"abstract":"<div><div>This paper introduces a method for constructing high-fidelity digital rock using digital grinding and deep learning, specifically for the Four-Dimensional Lattice Spring Model (4D-LSM). Initially, rock sequence images are captured with a self-designed digital grinding equipment. Bicubic interpolation is then applied to fill missing pixels, ensuring uniform resolution. The images are subsequently deblurred using DeblurGAN, a deep learning network trained with existing high-definition images. This process results in high-fidelity 3D true-color digital rock geometry reconstruction. An Artificial Neural Network (ANN) identifies mineral components, which are then mapped into the 4D-LSM to create the high-fidelity 3D true-color Grain-Based Model (GBM). The mechanical behavior of the GBM is analyzed using the 4D-LSM, incorporating strength reduction factors which can be easily calibrated through a modified Newton algorithm. Results demonstrate that the high-fidelity 3D true-color GBM accurately replicates the mechanical behavior and failure processes of granite, offering improved consistency with experimental data compared to homogeneous models.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"186 ","pages":"Article 106004"},"PeriodicalIF":7.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142874840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.ijrmms.2025.106036
Luchao Wang , Kang Duan , Qiangyong Zhang , Xiufeng Zhang , Chuancheng Liu , Di Wang
Deepening the understanding of the dynamic propagation and interaction of multiple hydraulic fractures is the key to the optimization of hydraulic fracturing design. By conducting two-hole hydraulic fracturing experiments on transparent polymethyl methacrylate (PMMA) samples, we visualize the dynamic propagation of fractures stimulated from two holes in three dimensions with the aid of high-speed cameras and image reconstruction methods. The characteristics of hydraulic fracture growth were discussed in conjunction with extended finite element method (XFEM) simulation and theoretical analysis. The competition between the boundary stress and the internal stress from the holes controls the growth mode of the fractures. The reduction of boundary stress difference intensifies the stress concentration between holes, resulting in the transformation of planar fractures formed from a single hole into spiral fractures connecting two holes. The propagation of double-hole spiral fractures can be divided into hole connection, deflection and rapid propagation stages. The fractures first connect the two holes dominated by the stress concentration, and then reoriente to the σH direction under the control of the boundary stress. The propagation of single-hole planar fractures can be divided into upward propagation, bilateral synchronization and downward propagation stages. The fracture propagating in the σH direction first appears on the single-hole side under the control of boundary stresses, and then deflects towards the adjacent hole influenced by the attraction stresses from adjacent holes. The propagation of two-hole hydraulic fractures has obvious sequence, and the stress repulsion of the primary fracture makes the secondary fracture propagate in opposite direction.
{"title":"Visualization of the dynamic propagation of two simultaneously-stimulated hydraulic fractures: Competition and interaction","authors":"Luchao Wang , Kang Duan , Qiangyong Zhang , Xiufeng Zhang , Chuancheng Liu , Di Wang","doi":"10.1016/j.ijrmms.2025.106036","DOIUrl":"10.1016/j.ijrmms.2025.106036","url":null,"abstract":"<div><div>Deepening the understanding of the dynamic propagation and interaction of multiple hydraulic fractures is the key to the optimization of hydraulic fracturing design. By conducting two-hole hydraulic fracturing experiments on transparent polymethyl methacrylate (PMMA) samples, we visualize the dynamic propagation of fractures stimulated from two holes in three dimensions with the aid of high-speed cameras and image reconstruction methods. The characteristics of hydraulic fracture growth were discussed in conjunction with extended finite element method (XFEM) simulation and theoretical analysis. The competition between the boundary stress and the internal stress from the holes controls the growth mode of the fractures. The reduction of boundary stress difference intensifies the stress concentration between holes, resulting in the transformation of planar fractures formed from a single hole into spiral fractures connecting two holes. The propagation of double-hole spiral fractures can be divided into hole connection, deflection and rapid propagation stages. The fractures first connect the two holes dominated by the stress concentration, and then reoriente to the σ<sub>H</sub> direction under the control of the boundary stress. The propagation of single-hole planar fractures can be divided into upward propagation, bilateral synchronization and downward propagation stages. The fracture propagating in the σ<sub>H</sub> direction first appears on the single-hole side under the control of boundary stresses, and then deflects towards the adjacent hole influenced by the attraction stresses from adjacent holes. The propagation of two-hole hydraulic fractures has obvious sequence, and the stress repulsion of the primary fracture makes the secondary fracture propagate in opposite direction.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"186 ","pages":"Article 106036"},"PeriodicalIF":7.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143049661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.ijrmms.2024.105975
Yinjiang Nie, Yanlong Zheng, Jianchun Li
Existing numerical models cannot well reproduce the fracturing process and reveal the underlying mechanisms of rocks under microwave irradiation. In this work, the electromagnetic-thermal-mechanical multiphysics is decoupled into microwave-induced heating (continuum-based) and thermally-driven fracturing (discontinuum-based), with temperature serving as the key interlink. The rigid-body spring-subset network (RBSSN) model is proposed to calculate the progressive fracturing of rocks under open-ended microwave irradiation, where the individual contacts between adjacent tetrahedral blocks are disassembled into three hypothetical spring-subsets. To depict failure characteristics of large-scale rocks under microwave irradiation, a variable-sized block model is developed by densifying the rigid-blocks near the irradiation. This electromagnetic-thermal-mechanical decoupling framework effectively captures the microwave fracturing process, revealing that microwave irradiation induces tensile-dominant progressive failure and regionalized deterioration (localized damage and macroscopic radial fissure). The fracturing rate of rocks is time-dependent, progressing through silent, violent and slowdown periods of rupturing with extended exposure time. The reason why high-power microwave is more effective in promoting visible fractures under the identical input energy is analyzed by combining the thermal deformation theory and RBSSN simulation. It is found that, power levels should be kept within reasonable scopes to maximize fracturing effects as excessive power densities lead to initiation of numerous microcracks around the high temperature zone and susceptibility to spalling.
{"title":"Modelling microwave fracturing of rocks: A continuum-discontinuum numerical approach","authors":"Yinjiang Nie, Yanlong Zheng, Jianchun Li","doi":"10.1016/j.ijrmms.2024.105975","DOIUrl":"10.1016/j.ijrmms.2024.105975","url":null,"abstract":"<div><div>Existing numerical models cannot well reproduce the fracturing process and reveal the underlying mechanisms of rocks under microwave irradiation. In this work, the electromagnetic-thermal-mechanical multiphysics is decoupled into microwave-induced heating (continuum-based) and thermally-driven fracturing (discontinuum-based), with temperature serving as the key interlink. The rigid-body spring-subset network (RBSSN) model is proposed to calculate the progressive fracturing of rocks under open-ended microwave irradiation, where the individual contacts between adjacent tetrahedral blocks are disassembled into three hypothetical spring-subsets. To depict failure characteristics of large-scale rocks under microwave irradiation, a variable-sized block model is developed by densifying the rigid-blocks near the irradiation. This electromagnetic-thermal-mechanical decoupling framework effectively captures the microwave fracturing process, revealing that microwave irradiation induces tensile-dominant progressive failure and regionalized deterioration (localized damage and macroscopic radial fissure). The fracturing rate of rocks is time-dependent, progressing through silent, violent and slowdown periods of rupturing with extended exposure time. The reason why high-power microwave is more effective in promoting visible fractures under the identical input energy is analyzed by combining the thermal deformation theory and RBSSN simulation. It is found that, power levels should be kept within reasonable scopes to maximize fracturing effects as excessive power densities lead to initiation of numerous microcracks around the high temperature zone and susceptibility to spalling.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"186 ","pages":"Article 105975"},"PeriodicalIF":7.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142825400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Existence of discontinuous geological structures, such as folds and fault, poses a great challenge in predicting the in-situ stress fields (ISSF). This paper proposes a discontinuous intelligent inversion method to predict the ISSFs in the deep coal seam area (DCSA) of the Shanghai Temple, which exhibits distinct discontinuous geological features. The proposed method consists of three key components. First, a discontinuous loading model was developed to address the problem of accuracy in the numerical simulation of discontinuous tectonic regions such as folds and faults. The simulation data generated is used as a sample dataset for the training of the inversion algorithm and their completeness is fully guaranteed. Second, the statistical distribution patterns of horizontal, maximum and minimum lateral pressure coefficients (LPCs) of the ISSF in the typical DCSAs of China is statistically calculated. By applying Gaussian- and Cauchy-type fuzzy membership functions, the degree of influence of faults and folds on the local ISSF is quantified and the geological structure influence model is constructed. The influence value enriches the input data dimension of the algorithm and lays a more detailed data foundation for the stress inversion. Third, the improved Long Short-Term Memory (LSTM) network algorithm was constructed by optimizing the network hierarchy and multi-parameter cyclic learning. An inversion analysis is carried out using the ISSF around the borehole as an example, and the relative error strictly controlled within 1 %. The improved LSTM algorithm achieves an accuracy of 88.58 % at each measurement point in the Shanghai Temple deep coal seam project, which is significantly higher than that of the back propagation neural network (BPNN). The discontinuous intelligent inversion method proposed in this study can provide an effective tool for predicting the ISSF in DCSA.
{"title":"A nonlinear inversion method for predicting the in-situ stress field in deep coal seam based on improved long short-term memory neural network","authors":"Jiaxing Zhou , Bisheng Wu , Yuanxun Nie , Haitao Zhang","doi":"10.1016/j.ijrmms.2024.106020","DOIUrl":"10.1016/j.ijrmms.2024.106020","url":null,"abstract":"<div><div>Existence of discontinuous geological structures, such as folds and fault, poses a great challenge in predicting the in-situ stress fields (ISSF). This paper proposes a discontinuous intelligent inversion method to predict the ISSFs in the deep coal seam area (DCSA) of the Shanghai Temple, which exhibits distinct discontinuous geological features. The proposed method consists of three key components. First, a discontinuous loading model was developed to address the problem of accuracy in the numerical simulation of discontinuous tectonic regions such as folds and faults. The simulation data generated is used as a sample dataset for the training of the inversion algorithm and their completeness is fully guaranteed. Second, the statistical distribution patterns of horizontal, maximum and minimum lateral pressure coefficients (LPCs) of the ISSF in the typical DCSAs of China is statistically calculated. By applying Gaussian- and Cauchy-type fuzzy membership functions, the degree of influence of faults and folds on the local ISSF is quantified and the geological structure influence model is constructed. The influence value enriches the input data dimension of the algorithm and lays a more detailed data foundation for the stress inversion. Third, the improved Long Short-Term Memory (LSTM) network algorithm was constructed by optimizing the network hierarchy and multi-parameter cyclic learning. An inversion analysis is carried out using the ISSF around the borehole as an example, and the relative error strictly controlled within 1 %. The improved LSTM algorithm achieves an accuracy of 88.58 % at each measurement point in the Shanghai Temple deep coal seam project, which is significantly higher than that of the back propagation neural network (BPNN). The discontinuous intelligent inversion method proposed in this study can provide an effective tool for predicting the ISSF in DCSA.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"186 ","pages":"Article 106020"},"PeriodicalIF":7.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142974938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.ijrmms.2025.106039
Qazim Llabjani , Alessio Ferrari , Paul Marschall , Lyesse Laloui
Disposal of radioactive waste in deep geological repositories relies on the integrity of geological barriers, where gas migration can compromise long-term safety. This study examines the hydro-mechanical response of a shale under varying gas pressure build-up rates, using gas injection tests conducted in a high-pressure oedometer cell to simulate in-situ stress conditions. The research highlights that gas-induced porewater redistribution plays a key role during gas invasion processes. Results indicate that rapid gas pressure build-up leads to undrained conditions associated with significant porewater pressure development and expansive strains, while slower gas injection results in a drained response with less deformation. Additionally, a delayed gas breakthrough during rapid pressure build-up suggests the impedance of gas movement by porewater. However, once steady-state is achieved, both tests converge to similar gas flow rates and equilibrium states, indicating that the long-term gas transport properties of Opalinus Clay, selected as the host geomaterial for the Swiss repository, are not significantly influenced by initial gas pressure rates. Furthermore, neither the water intrinsic permeability nor the pore size distribution of the material is altered by gas invasion, highlighting the robustness of Opalinus Clay as a geological barrier for radioactive waste disposal. These findings emphasize the importance of understanding both short-term and long-term hydro-mechanical responses of shales subjected to gas transport to ensure the long-term containment and isolation of radioactive waste.
{"title":"Hydro-mechanical insights for radioactive waste disposal from gas injection experiments in shale","authors":"Qazim Llabjani , Alessio Ferrari , Paul Marschall , Lyesse Laloui","doi":"10.1016/j.ijrmms.2025.106039","DOIUrl":"10.1016/j.ijrmms.2025.106039","url":null,"abstract":"<div><div>Disposal of radioactive waste in deep geological repositories relies on the integrity of geological barriers, where gas migration can compromise long-term safety. This study examines the hydro-mechanical response of a shale under varying gas pressure build-up rates, using gas injection tests conducted in a high-pressure oedometer cell to simulate in-situ stress conditions. The research highlights that gas-induced porewater redistribution plays a key role during gas invasion processes. Results indicate that rapid gas pressure build-up leads to undrained conditions associated with significant porewater pressure development and expansive strains, while slower gas injection results in a drained response with less deformation. Additionally, a delayed gas breakthrough during rapid pressure build-up suggests the impedance of gas movement by porewater. However, once steady-state is achieved, both tests converge to similar gas flow rates and equilibrium states, indicating that the long-term gas transport properties of Opalinus Clay, selected as the host geomaterial for the Swiss repository, are not significantly influenced by initial gas pressure rates. Furthermore, neither the water intrinsic permeability nor the pore size distribution of the material is altered by gas invasion, highlighting the robustness of Opalinus Clay as a geological barrier for radioactive waste disposal. These findings emphasize the importance of understanding both short-term and long-term hydro-mechanical responses of shales subjected to gas transport to ensure the long-term containment and isolation of radioactive waste.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"186 ","pages":"Article 106039"},"PeriodicalIF":7.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.ijrmms.2025.106034
Bozo Vazic, Eric C. Bryant, Kane C. Bennett
A unified objective optimization framework is developed for damage-coupled multisurface plasticity in the context of normal-dissipative media. The framework is shown to be advantageous in rock and soil mechanics applications to overcome difficulty associated with non-smoothness of the elastic domain due to the use of multiple intersecting yield-surfaces. The basic approach is one of mathematical programming, where the evolution of internal variables over a finite time step incrementally minimizes a suitable convex functional of the internal-energy and dissipative terms. A variant of the Broyden–Fletcher–Goldfarb–Shanno algorithm (BFGS) is employed to obviate the need for matrix inversion while constricting order of operations to . To demonstrate the effectiveness of the novel multi-surface model in modeling strength and damage behavior over a range of confining pressures, we provide validation against existing triaxial compression data for Tavel limestone. Model robustness and utility in damage-based element deletion is further demonstrated in finite element simulation of a projectile penetrating into limestone.
{"title":"Single objective optimization for modeling elastoplastic damage of rock","authors":"Bozo Vazic, Eric C. Bryant, Kane C. Bennett","doi":"10.1016/j.ijrmms.2025.106034","DOIUrl":"10.1016/j.ijrmms.2025.106034","url":null,"abstract":"<div><div>A unified objective optimization framework is developed for damage-coupled multisurface plasticity in the context of normal-dissipative media. The framework is shown to be advantageous in rock and soil mechanics applications to overcome difficulty associated with non-smoothness of the elastic domain due to the use of multiple intersecting yield-surfaces. The basic approach is one of mathematical programming, where the evolution of internal variables over a finite time step incrementally minimizes a suitable convex functional of the internal-energy and dissipative terms. A variant of the Broyden–Fletcher–Goldfarb–Shanno algorithm (BFGS) is employed to obviate the need for matrix inversion while constricting order of operations to <span><math><mrow><mi>O</mi><mrow><mo>(</mo><msup><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo></mrow></mrow></math></span>. To demonstrate the effectiveness of the novel multi-surface model in modeling strength and damage behavior over a range of confining pressures, we provide validation against existing triaxial compression data for Tavel limestone. Model robustness and utility in damage-based element deletion is further demonstrated in finite element simulation of a projectile penetrating into limestone.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"186 ","pages":"Article 106034"},"PeriodicalIF":7.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.ijrmms.2024.105985
Ishmael Dominic Yevugah , Xiang-Zhao Kong , Antoine B. Jacquey , Christopher P. Green , Hartmut M. Holländer , Pooneh Maghoul
In domal and bedded rock salt geothermal reservoirs, geochemical dissolution of the in-situ rock salt formation can alter fluid transport properties, thus impacting fluid flow. Coupled Hydro-mechanical–chemical (HMC) modeling is a useful tool to evaluate fluid transport through rock salt geothermal systems and to assess their economic potential. Existing continuum-based numerical simulation of fluid transport through rock salt relies on the polyhedral orientation of rock salt crystal boundaries as potential fluid pathways, employing a deformation-dependent permeability model to depict pressure-driven fluid flow through rock salt. However, this numerical approach is exclusively HM-coupled and overlooks the influence of halite dissolution/precipitation on the permeability model. This study extends the deformation-dependent permeability model to account for halite dissolution by adopting a reverse mineral growth approach. Using this extended (HMC-coupled) model, we capture the relevance of geochemical reactions on the response of rock salt formations undergoing pressure-driven fluid percolation. The resulting simulations predict a lower fluid pressure than the HM-coupled scenario, highlighting the impact of halite dissolution on fluid flow through rock salt.
{"title":"Fully coupled hydro-mechanical–chemical continuum modeling of fluid percolation through rock salt","authors":"Ishmael Dominic Yevugah , Xiang-Zhao Kong , Antoine B. Jacquey , Christopher P. Green , Hartmut M. Holländer , Pooneh Maghoul","doi":"10.1016/j.ijrmms.2024.105985","DOIUrl":"10.1016/j.ijrmms.2024.105985","url":null,"abstract":"<div><div>In domal and bedded rock salt geothermal reservoirs, geochemical dissolution of the in-situ rock salt formation can alter fluid transport properties, thus impacting fluid flow. Coupled Hydro-mechanical–chemical (HMC) modeling is a useful tool to evaluate fluid transport through rock salt geothermal systems and to assess their economic potential. Existing continuum-based numerical simulation of fluid transport through rock salt relies on the polyhedral orientation of rock salt crystal boundaries as potential fluid pathways, employing a deformation-dependent permeability model to depict pressure-driven fluid flow through rock salt. However, this numerical approach is exclusively HM-coupled and overlooks the influence of halite dissolution/precipitation on the permeability model. This study extends the deformation-dependent permeability model to account for halite dissolution by adopting a reverse mineral growth approach. Using this extended (HMC-coupled) model, we capture the relevance of geochemical reactions on the response of rock salt formations undergoing pressure-driven fluid percolation. The resulting simulations predict a lower fluid pressure than the HM-coupled scenario, highlighting the impact of halite dissolution on fluid flow through rock salt.</div></div>","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"186 ","pages":"Article 105985"},"PeriodicalIF":7.0,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142825393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.ijrmms.2024.106010
Quangui Li , Wenxi Li , Qianting Hu , Yunpei Liang , Yanan Qian , Zhizhong Jiang , Zhen Wang , Huiming Yang , Wanjie Sun
Before effectively analyzing the stimulation of coalbed methane (CBM) reservoirs using microseismic (MS) monitoring, it is necessary to accurately distinguish signals caused by hydraulic fracturing (HF) from interference signals. In this study, the Mel-frequency cepstral coefficient-fuzzy decision tree (MFCC-FDT) signal classification method was used. To minimize the loss of crucial details during preprocessing, feature extraction is accomplished by computing the MFCC values. This is followed by a decrease in the dimensionality and fuzzification of the dataset. Finally, the preprocessed data are entered into the FDT classifier that has been trained, thereby completing the automated identification of the induced signals. The proposed technique was applied to examine MS signals during the staged HF stimulation of a CBM reservoir. These findings suggest that the MFCC-FDT method outperforms the other combinations in terms of Accuracy, Precision, Recall, and F1-Score. Thirty-five interference MS events, including signals from tunneling blasts and machine operation during reservoir stimulation, were eliminated. The total stimulated reservoir volume under the MFCC-FDT technique validation was 22 966.29 m3, 1954.34 m3 less than the volume prior to the interference signals being removed. The proposed method reveals the nonlinear frequency characteristics of the induced MS signals and can be utilized to render more accurate MS signals for quantifying CBM reservoir stimulation by subsequent source inversion.
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